Aircraft: B777
Phase of flight: Cruise
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy

Enroute to ZZZZ FL320; the EICAS displayed 'fuel valve'; we completed the relevant checklist which only said don't takeoff and that the engine may be slower to shut down.We viewed the FUEL synoptic and all three displays were identical; there was no green fuel flow diagram to the left engine and the valve was an orange circle with an X in it.Per our manual this meant that said valve had failed; valve was commanded closed buy stayed open.Using SATCOM; was unsuccessful to contact the company dispatcher and maintenance people. Finally we used ARINC and during the discussions we got a status message saying 'fuel spar valve L.'We couldn't ascertain that ETOPS entry was allowed; whether the valve would remain open; if we would be able to easily shutdown said engine if required; [Maintenance Control] couldn't guarantee any of these.Using the fuel synoptic and in discussion with [Maintenance Control] we learned that if we had to cross feed fuel that this wouldn't display properly on the fuel synoptic to further verify the fuel switches were in fact doing what we commanded; much like any autopilot; you push the buttons AND VERIFY that the action occurred. We don't blindly trust without verifying; that kills.We asked if this part/failure was in the MEL; [Maintenance Control] said it was not. It is a no-go item.We; three pilots; discussed this situation very carefully; thinking of options. With safety the entire focus we chose unanimously to not enter ETOPS/continue the flight to ZZZZ a further 8-9 hours hoping that all was safe. The [Chief Pilot] spoke to us briefly; I felt they wanted us to continue the flight to ZZZZ. During this time we lost communications with dispatch and [Maintenance Control] many times; and eventually relied upon ACARS.We shared our decision with our dispatcher who did an excellent job especially as communications was not easy; and we offered to divert to any hub where another plane could speedily take the passengers onto ZZZZ asap and where we had maintenance that could correctly replace/repair this failed equipment.We offered [several airport choices. One] had bad weather. Dispatch chose ZZZ1. So we informed [Center]; and got clearance back to ZZZ1.We brought up the Purser; and explained the situation; that all was safe and that we were going to ZZZ1; after she informed the rest of the crew we briefed the passengers; that they were very safe; that we had a minor mechanical malfunction; that they had around 100 years of flight experience in the cockpit and many more with the crew; and that the company was working to get them to ZZZZ asap.Due to landing weight restrictions; working with ATC and dispatch we chose to jettison fuel and did so safely. The rest of the flight was uneventful and safe. ATC both in Canada and the USA was excellent; and patient. Thank you.My entire crew did the safest course; was very thoughtful; and didn't take making the decision lightly; safety is paramount. [Report narrative contained no additional information.] B777 flight crew reported an in flight failure of a fuel valve which compromised continuing into ETOPS operation; and resulted in a return to the departure airport.